// Copyright 2014 The Chromium Authors. All rights reserved.
// Use of this source code is governed by a BSD-style license that can be
// found in the LICENSE file.

#ifndef UI_BASE_ACCELERATORS_ACCELERATOR_HISTORY_H_
#define UI_BASE_ACCELERATORS_ACCELERATOR_HISTORY_H_

#include "base/macros.h"
#include "base/memory/singleton.h"
#include "ui/base/accelerators/accelerator.h"
#include "ui/base/ui_base_export.h"
#include "ui/events/event.h"
#include "ui/events/event_handler.h"

namespace ui {

// Keeps track of the system-wide current and the most recent previous
// key accelerators.
class UI_BASE_EXPORT AcceleratorHistory {
public:
    AcceleratorHistory();
    ~AcceleratorHistory();

    // Returns the most recent recorded accelerator.
    const Accelerator& current_accelerator() const
    {
        return current_accelerator_;
    }

    // Returns the most recent previously recorded accelerator that is different
    // than the current.
    const Accelerator& previous_accelerator() const
    {
        return previous_accelerator_;
    }

    // Stores the given |accelerator| only if it's different than the currently
    // stored one.
    void StoreCurrentAccelerator(const Accelerator& accelerator);

private:
    Accelerator current_accelerator_;
    Accelerator previous_accelerator_;

    DISALLOW_COPY_AND_ASSIGN(AcceleratorHistory);
};

}; // namespace ui

#endif // UI_BASE_ACCELERATORS_ACCELERATOR_HISTORY_H_
